Câu hỏi:

There are more than one billion cows in the world, and cow farming is a large source of methane emissions. This colorless and odorless gas (631) ____ at warming the earth.

Farmers and companies are developing solutions for (632) _____. In Canada and Brazil, farmers started adding a special ingredient to their animals' feed to reduce cows' methane production. In New Zealand, scientists are working on a vaccine which can cut methane emissions. Rather than stopping methane emissions, a UK company has designed face masks to catch the gas (633) ______.

The masks will allow cows to continue their normal diet but will turn methane into CO2 and water. They can fit comfortably on the cow's head and can be adjusted to different head sizes. Sensors on the masks can notice when methane comes out of the cow's mouth and provide the percentage of the gas (634)_____. This information can also be useful for farmers who can use it to (635) __________ the early signs of disease. For example, if a cow eats less, but produces more methane than usual, it may have a health problem.

It is predicted that the need for beef and dairy products will go up in the coming years. The company developing the methane-catching masks hopes that farmers will start using their invention, which will slow down global warming.

Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each the numbered blanks